Wildlife, offshore wind turbines a bad mix

[XemaSab]

I have fished Padre Island for 53 years and have been the only licensed fishing guide and naturalist providing tours on the National Seashore for the past 22 years. On average I am down island about 128 days per year. I am the founder of the Big Shell Beach Cleanup and have been its primary organizer for the past 17 years. During that time, 2.3 million pounds of debris has been removed by this volunteer effort. In 2010, I was chosen as one of the six Heroes of Conservation by Field & Stream Magazine. I received the first ever Lifetime Conservation Award from the Coastal Conservation Association and this year was the popular choice winner of the Making a Difference Award competition sponsored by Sports Fishing Magazine.

Hopefully this qualifies me to comment on the natural resources of the Coastal Bend.

In early September I encountered what I roughly estimated were 750,000 black terns on Padre Island National Seashore. This represents only a fraction of the native and migratory birds on the island. Padre is recognized as a Globally Important Bird Area by the American Bird Conservancy and a site of hemispheric importance by the Western Hemisphere Shorebird Reserve Network.

Following that sighting of black terns I spent the next seven days and a night down island. The number of birds I counted fluctuated greatly. One day I'd see 300 to 400 terns and on another day I estimated 350,000 birds. This was not a migration in or out of the area. On the contrary, the birds were coming and going to feed on incoming schools of dusky anchovies that wander near shore and offshore this time of year. When these huge shoals of anchovies are five or 10 miles offshore the birds follow, but they don't return to shore when they're not feeding. They simply sleep on the water to remain near their prey. All pelagic and shore birds that eat fish are attracted to schools of anchovies, menhaden and other such foraging species.

http://www.caller.com/news/2011/oct/25/wildlife-offshore-wind-turbines-a-bad-mix/

[OKIsItJustMe]

1. As with all turbines, site selection matters

Anything as tall as a wind turbine off Padre Island would likely be a bad mix.

[kristopher]

2. Tracking real-life activity around an offshore wind farm

The westerly oriented flight trajectories during the initial operation of the wind turbines. Black lines indicate migrating waterbird flocks, red dots the wind turbines. Scale bar, 1000m.

Avian collision risk at an offshore wind farm
Mark Desholm* and Johnny Kahlert
Department of Wildlife Ecology and Biodiversity, National Environmental Research Institute, Grenåvej 12, 8410 Rønde, Denmark
Abstract
We have been the first to investigate whether long-lived geese and ducks can detect and avoid a large offshore wind farm by tracking their diurnal migration patterns with radar. We found that the percentage of flocks entering the wind farm area decreased significantly (by a factor 4.5) from pre-construction to initial operation. At night, migrating flocks were more prone to enter the wind farm but counteracted the higher risk of collision in the dark by increasing their distance from individual turbines and flying in the corridors between turbines. Overall, less than 1% of the ducks and geese migrated close enough to the turbines to be at any risk of collision.

Full article available here:
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1617151/

The image available by PDF at the supplement is even more striking. The density of overall avian traffic is even greater than the above image leads you to believe.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1617151/bin/rsbl20050336s04.pdf

[OKIsItJustMe]

3. Data! Real live data!

I love it!


Mind you, just the other day I saw a bird fly into one of our windows. Our house was not moving at the time, and (to my knowledge) has not moved for more than a century…

[kristopher]

4. Did you look at the esupplementary material?

Also, I just found this listed as a related article. The conclusion surprised me, but I haven't had a chance to read it yet.

Collision Mortality Has No Discernible Effect on Population Trends of North American Birds
Todd W. Arnold1* and Robert M. Zink2
1Department of Fisheries, Wildlife, and Conservation Biology, University of Minnesota, St. Paul, Minnesota, United States of America
2Bell Museum and Department of Ecology, Evolution and Behavior, University of Minnesota, St. Paul, Minnesota, United States of America
Brock Fenton, Editor
University of Western Ontario, Canada
Conceived and designed the experiments: TWA RMZ. Analyzed the data: TWA. Wrote the paper: TWA RMZ.

Abstract
Avian biodiversity is threatened by numerous anthropogenic factors and migratory species are especially at risk. Migrating birds frequently collide with manmade structures and such losses are believed to represent the majority of anthropogenic mortality for North American birds. However, estimates of total collision mortality range across several orders of magnitude and effects on population dynamics remain unknown. Herein, we develop a novel method to assess relative vulnerability to anthropogenic threats, which we demonstrate using 243,103 collision records from 188 species of eastern North American landbirds. After correcting mortality estimates for variation attributable to population size and geographic overlap with potential collision structures, we found that per capita vulnerability to collision with buildings and towers varied over more than four orders of magnitude among species. Species that migrate long distances or at night were much more likely to be killed by collisions than year-round residents or diurnal migrants. However, there was no correlation between relative collision mortality and long-term population trends for these same species. Thus, although millions of North American birds are killed annually by collisions with manmade structures, this source of mortality has no discernible effect on populations.

Full article available here:
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3170378/?tool=pubmed

[OKIsItJustMe]

5. I did look at the supplemental material

Regarding the second study, that is surprising (at least the tables of relative collision rates were surprising.)

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3170378/bin/pone.0024708.s003.pdf
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3170378/bin/pone.0024708.s004.pdf

I happen to know a bird researcher… I think I’ll get her take on it…

[kristopher]

6. I can see at least one plausible line of reasoning...

There has possibly been a trade off between lost habitat and reduced predation. Just look at the numbers taken by cats and imagine the effects of natural predators for birds on the N. Amer continent before the influence of humans made itself felt. We aren't the only critters that like eggs...